This application claims the benefit of Japanese Application No. 2000-229510 filed in Japan on Jul. 28, 2000, the contents of which are incorporated by this reference.
1. Field of the Invention
The present invention relates to an endoscope having a flexible insertion member with different hardness for bending in a predetermined area of the longitudinal direction thereof.
2. Related Art Statement
Conventionally, wide use has been made of a medical endoscope capable of observing organs in a body cavity or conducting various medical treatments using a therapeutic instrument passed through a therapeutic instrument channel, if necessary, by inserting a slender insertion member into the body cavity.
The endoscope used in the medical field enables therapy or treatment by inserting the insertion member into a body cavity to observe organs or to conduct various medical treatments using the therapeutic instrument passed through a therapeutic instrument channel of the endoscope.
For example, an endoscope inserted into the colon requires the capability of ease of operation and flexibility to a large extent after inserting the insertion member. In other words, flexibility (softness) is required for the distal part of the insertion member to enable insertion along a bent passage. On the other hand, a predetermined amount of stiffness (also called hardness) is required for the proximal part of the insertion member after the operator inserts the distal part of the insertion member. Accordingly, there are endoscopes having various kinds of designs/devices on the resin of a sheathing member of the insertion member so as to be capable of performing these features.
For example, Japanese Laid-Open Patent Application (Tokukaihei) No. 2-283346 discloses a flexible tube for an endoscope at least containing the common polymer material in each layer of the double laminated polymer material layers of the sheathing member.
Endoscope devices used in the medical field have required cleaning and disinfection after an individual endoscopic examination and treatment to prevent infection among patients when re-using the device for other patients.
In recent years, the autoclave sterilization method (high pressure steam sterilization), which is not complicated and is capable of being used immediately after sterilization, and which is inexpensive in terms of running costs is becoming the mainstream of the sterilization treatment for the disinfection of medical devices.
For example, Japanese Laid-Open Patent Application No.5-285103 discloses an autoclaving device for an endoscope which is capable of autoclave sterilization without deteriorating the function of the endoscope.
The environment of steam sterilization under pressure is extremely harsh for a precision electronic instrument such as endoscope. Therefore, to produce an endoscope being resistant to this condition, various measures relating to high pressure, high temperature, and steam are taken in comparison with a general purpose endoscope which is designed to be used in a general cleaning and disinfection manner.
However, in accordance with the flexible tube for the endoscope disclosed in the Japanese Laid-Open Patent Application 2-283346, the polymer resin of the sheathing member of an insertion member deteriorates by the heat generated upon steam sterilization of the endoscope under pressure. Also, the problem arises that the resin of the sheathing member of the flexible tube for the endoscope is subject to deterioration and alteration over time.
Furthermore, once the resin of the sheathing member deteriorates, the stiffness for bending of the insertion member in a predetermined length of longitudinal direction is altered compared with the initial state. As a result, a problem arises in that it becomes hard for users to appropriately insert.
The object of present invention is to provide an endoscope capable of being inserted smoothly for an extended period, even if the sheathing member layer has deteriorated or become altered after extended use or after repetitive steam sterilization of the endoscope under high pressure.
Briefly, the present invention relates to a flexible endoscope comprising a flexible insertion member having different hardness in bending in a predetermined area in the longitudinal direction. This insertion member includes a flexible tube having a resin sheathing layer on the outside and slender inner parts passing through the flexible tube. An amount of change in the hardness level for bending the inner parts in the longitudinal direction is designed to be larger than an amount of change in the hardness level for bending the sheathing layer of the flexible tube in the longitudinal direction so as to maintain the ability to insert the endoscope smoothly for extended periods of time, even after the sheathing layer has deteriorated or become altered.